A method for blending slurry and latex in rubber production
By using mechanical shearing and mixing with gas jet dispersion, the complexity and performance degradation issues of the blending process of slurry and rubber solution in rubber production have been solved, achieving more efficient dispersion and performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 益凯新材料有限公司
- Filing Date
- 2023-10-31
- Publication Date
- 2026-07-28
AI Technical Summary
The existing rubber production process of blending slurry and rubber solution has problems such as complicated process, high cost and deterioration of rubber performance.
The method employs a combination of mechanical shearing and stirring with gas jet dispersion. By varying the speed and direction of stirring, the slurry and adhesive are rapidly and fully dispersed, and the temperature is controlled to improve dispersibility.
It improves the dispersibility and performance of rubber, simplifies the process, and reduces production costs.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of new materials technology, specifically to a method for blending slurry and adhesive solution suitable for rubber production. Background Technology
[0002] Mixing refers to the process of adding various compounding agents, such as fillers, reinforcing agents, accelerators, vulcanizing agents, antioxidants, and scorch inhibitors, to raw rubber or plastic rubber to improve the physical and mechanical properties of rubber products, optimize processing and molding techniques, and reduce production costs. These compounding agents can be solid or liquid materials. The goal is to disperse all the added compounding agents evenly to ensure the consistency of the rubber compound's properties. Therefore, mixing is essentially the process of uniformly dispersing compounding agents or fillers in raw rubber. After dispersion, the granular compounding agents are in the dispersed phase, while the raw rubber is in the continuous phase.
[0003] Mixing is the most crucial step in rubber compound processing. Fillers and various additives undergo not only physical changes with the rubber compound but also some chemical reactions. Currently, raw rubber or plasticized raw rubber is typically mixed with compounding agents using a rubber mixing mill to form a compound, including dry mixing and wet mixing. Dry mixing involves batch or continuous mixing of fillers with solid rubber or granules. In recent years, liquid-phase mixing has become a research hotspot. This method involves mixing polymer latex and filler slurry and preparing masterbatch through chemical coagulation. However, the chemical agents in this method adsorb onto the filler surface, hindering the interaction between the polymer and filler; moreover, the filler-bound rubber has high hardness, making it difficult to cut and further process. Directly pulverizing latex particles from the emulsion under the combined action of a separating agent and a coagulant can improve the processing performance of the masterbatch to some extent.
[0004] CN104893024B discloses a method for blending natural latex with precipitated silica. The method involves sequentially adding organic acids to an aqueous solution of natural latex under ambient temperature and pressure, stirring, then adding an emulsifier, and continuing stirring, maintaining the solution pH at 5.5-7.0 throughout the stirring process. Next, silica slurry is added and mixed, with the pH maintained at 9-10 during stirring by adding an alkali metal hydroxide solution. This method blends liquid silica with natural latex, improving the dispersibility and uniformity of silica in the rubber, resulting in tires with low rolling resistance and requiring less energy during the mixing process.
[0005] CN104629123B discloses a method for mixing carbon black into powdered rubber, comprising preparing a paste-like carbon black slurry in a high-speed stirrer, controlling the stirring speed at 10,000-30,000 r / min; adding the carbon black slurry to rubber latex in two stages, first adding 1 / 5-1 / 2 of the carbon black slurry dropwise, controlling the temperature at 40-50℃, and stirring at 200-10,000 r / min, continuing stirring for 10-30 min after the addition is complete, then adding the remaining carbon black slurry, controlling the reaction temperature at 70-80℃, and stirring for 10-30 min; washing and dehydrating the resulting slurry to obtain the powdered rubber product. This method utilizes the adsorption effect of carbon black, supplemented by high-intensity mechanical shearing, to coagulate the latex into powder, without adding coagulants, separating agents, or other additives during the preparation process.
[0006] All of the above methods employ a process route of first preparing fillers or reinforcing materials into a slurry, and then mixing it with the adhesive. However, there are certain problems in the preparation process, such as the need to add organic acids or add them in batches, which can lead to a decrease in rubber performance or complicated processes that increase manufacturing costs. Summary of the Invention
[0007] To address the aforementioned technical problems, this invention provides a method for blending slurry and adhesive in rubber production. By preparing the filler into a slurry, and then employing a combination of mechanical shearing and stirring with gas jet dispersion, rapid and thorough dispersion of the slurry and adhesive is achieved, thereby improving the performance of the rubber.
[0008] The complete technical solution of this invention includes:
[0009] A method for blending slurry and adhesive solution suitable for rubber production includes the following steps:
[0010] (1) Slurry preparation
[0011] One or more mixtures of ingredients such as silica, silane coupling agent, zinc oxide, stearic acid and antioxidant are added to an organic solvent and stirred to obtain a slurry;
[0012] (2) Preparation of adhesive
[0013] Prepare single-component or multi-component rubber solutions;
[0014] (3) Mixing of slurry and adhesive
[0015] Rubber slurry is added to the mixing device, then the device is started and the silica slurry is added, and shearing, stirring and dispersing are performed.
[0016] Furthermore, in step (1), the slurry contains 10-150 parts of silica, 0-30 parts of silane coupling agent, 0-5 parts of zinc oxide, 0-4 parts of stearic acid, and 0-8 parts of antioxidant.
[0017] Furthermore, in step (1), the organic solvent is an alkane.
[0018] Furthermore, in step (1), the ratio of the formulation components to the solvent is 1:10 to 1:3, and the mixture is stirred at 20±10℃ for 1 to 10 hours to obtain a slurry.
[0019] Furthermore, the rubber compound may be natural rubber, styrene-butadiene rubber, cis-butadiene rubber, isoprene rubber, chloroprene rubber, nitrile rubber, or a mixture thereof.
[0020] Furthermore, the mixture includes a process of blending multiple adhesive liquids.
[0021] Furthermore, step (3) employs variable speed and variable direction stirring.
[0022] Furthermore, the slurry and adhesive mixture obtained by the method is further processed.
[0023] Furthermore, the method for preparing rubber using the mixture is characterized in that the mixture is coagulated and desolventized, filtered, dried, and then extruded and pressed into sheets to obtain the final rubber.
[0024] The advantages of this invention compared to existing technologies are as follows: This invention uses silica with good dispersibility assessment, employs slurry and adhesive mixture with shear stirring to improve dispersibility, and utilizes variable-speed, variable-direction stirring. After a stable flow field is formed, variable-frequency reverse stirring is performed, increasing the stirring speed and generating a larger stirring force. This breaks the already stable flow field of the adhesive, further dispersing the silica and fine particles in the slurry and achieving uniform distribution. Furthermore, controlling the temperature during the dispersion process improves the rubber properties. Attached Figure Description
[0025] Figure 1 This is a diagram of the condensation vessel used in this invention. Detailed Implementation
[0026] The technical solution of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are merely illustrative and are not intended to limit this application.
[0027] A method for blending slurry and adhesive solution suitable for rubber production includes the following steps:
[0028] (1) Slurry preparation
[0029] The ingredients are selected, including silica, coupling agent, softening oil, zinc oxide, stearic acid, antioxidant, and sulfur. The mass percentages are: silica 10-150 parts, silane coupling agent 0-30 parts, zinc oxide 0-5 parts, stearic acid 0-4 parts, and antioxidant 0-8 parts. One or more mixtures of the silica, silane coupling agent, zinc oxide, stearic acid, and antioxidant are added to an organic solvent. The organic solvent can be an alkane. The ratio of the formulation components to the solvent is 1:10 to 1:3. The mixture is stirred at 20±10℃ for 1-10 hours to obtain a slurry.
[0030] The preparation of silica slurry also includes:
[0031] 1) Quantitative assessment of the dispersibility of silica
[0032] For different batches of silica, the dispersibility of silica was evaluated for actual production purposes using the following method.
[0033] Rubber adhesive, silica, silane coupling agent, softener, and fines are selected and mixed using a mixer. This example includes five different batches of silica, as well as a reference group of silica. The reference group of silica can be selected from existing silica that meets performance standards and is used in actual production.
[0034] 1.1 First, the adhesive solution, silica, silane coupling agent, and fine particles were added sequentially. Softening oil was added after heating, and the reaction proceeded to silanization to obtain the test rubber. A total of six test rubbers were obtained by processing different batches of silica and a reference group of silica for each group.
[0035] 1.2 For each group of test rubbers, samples were prepared from 10 different locations, and their flowability was tested.
[0036] And the flow value F of the i-th group of rubber is calculated. i ;
[0037]
[0038] F j Let be the flow value of the j-th sample.
[0039] 1.3 The dispersion was obtained by processing the flow values of each group of rubbers:
[0040]
[0041] D i Let F be the dispersion degree of the i-th group of rubber. C The flow value is used as a reference for the rubber. A higher dispersibility indicates better dispersion of the silica. Silica with a dispersibility of not less than 0.98 was selected for rubber preparation.
[0042] (2) Preparation of adhesive
[0043] The adhesive used can be natural rubber, styrene-butadiene rubber, cis-butadiene rubber, isoprene rubber, chloroprene rubber, nitrile rubber, etc., or a mixture of the above rubbers. If it is a mixed adhesive, there is also a process of blending multiple adhesives.
[0044] The process of blending multiple adhesives involves an adhesive blending equipment with a basic structure and principle similar to CN110126114B. Multiple air inlets are added to the bottom of the cylinder, connected to injection pipes, which in turn are connected to a high-pressure air source. During blending, nitrogen gas is injected from the bottom of the cylinder through the air inlets. The gas forms bubbles in the adhesive and rises, simultaneously being broken up by the stirring shaft, causing the adhesive to exhibit a fluidized bed-like "boiling" state. This promotes thorough mixing and eliminates dead zones caused by shear mixing. The stirring shaft rotates at 500–1000 r / min. The gas pressure selection requires comprehensive consideration of the specific gravity, viscosity, and shear rate of the rubber adhesive. Practical verification has yielded an injection pressure of 1.5–3.0 MPa and a flow rate of 30–150 L / min. The blended adhesive is then obtained.
[0045] Temperature control can be used during the blending process, maintaining the temperature of the nitrogen gas being blown in between -20℃ and 0℃, and ensuring the temperature of the rubber solution does not exceed 30℃ during blending. This method improves the quality of the rubber solution and the properties of the rubber.
[0046] (3) Add rubber slurry to the mixing device, then start the device and add the slurry, slurry and softening oil, and perform shearing, stirring and dispersion. A preferred composition of the slurry and filler is: 100 parts slurry, 84 parts silica, 6.9 parts silane coupling agent, 2 parts softening oil, 3.5 parts zinc oxide, 2 parts stearic acid and 2.5 parts antioxidant.
[0047] The shearing and stirring device can be the equipment disclosed in CN110126114B. During the stirring process, both stirring motors are variable frequency motors, employing variable speed and direction stirring. Existing technologies for mixing slurry and adhesive typically use a fixed-speed shearing and stirring method. This method results in a relatively stable flow field during mixing, leading to some dead zones in the mixing process. Some agglomerated silica is difficult to disperse in this stable state, resulting in poor dispersion. To improve these problems, this invention employs a multi-stage variable frequency stirring method. During stirring, after a stable flow field is formed, variable frequency reverse stirring is performed, accelerating the stirring speed and generating a larger stirring force. This breaks the already stable flow field of the adhesive, further dispersing the silica and fine particles in the slurry, achieving uniform distribution. Verification showed that during the mixing process, the speed range was 500–1500 rpm, with 25 variable speed and direction stirring cycles. Each speed change had a speed difference of 400 rpm, and the speed change process was completed within 10 seconds, resulting in a speed acceleration greater than 40 r / ms. In the above process, the mixing temperature of the adhesive and slurry is controlled to avoid excessively high temperatures that would reduce the final rubber properties.
[0048] After the adhesive and slurry are blended, the organic solvent needs to be removed. Then, in a coagulation reactor, 95°C water is directly sprayed in at a pressure of 30 MPa for coagulation. The coagulation reactor is as follows: Figure 1 As shown, the coagulated and desolventized rubber particles are filtered and dried to obtain masterbatch. The desolventized rubber compound is then extruded and pressed to obtain the final rubber product.
[0049] The above-described embodiments are merely some implementation methods of this application. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this application, and these all fall within the protection scope of this application.
Claims
1. A method for blending slurry and adhesive solution suitable for rubber production, characterized in that, Includes the following steps: (1) Quantitative assessment of the dispersibility of silica and preparation of the adhesive solution Dispersibility assessments were conducted on different batches of silica. Rubber adhesive, silica, silane coupling agent, softener, and fines were selected and mixed using a mixer. Five groups of different batches of silica were produced, along with a reference group. The reference group consisted of existing silica with satisfactory performance used in actual production, including: (1.1) First, add the adhesive, silica, silane coupling agent and fine material in sequence, heat up and add softening oil, and after reaction, the test rubber is obtained. For each group, different batches of silica and reference silica are used to obtain a total of 6 groups of test rubber. (1.2) For each group of test rubbers, select 10 different locations of rubber to make samples, test their flowability, and calculate the flow value of the i-th group of rubbers. ; Let be the flow value of the j-th sample; (1.3) The dispersion was obtained by processing the flow values of each group of rubbers: Let be the dispersion degree of the i-th group of rubber. The flow value is for the reference group of rubber; Select silica with a dispersibility of not less than 0.98 for slurry preparation: add one or more mixtures of silica, silane coupling agent, zinc oxide, stearic acid and antioxidant to an organic solvent and stir to obtain slurry; (2) Preparation of adhesive solution A multi-component rubber compound is prepared; the rubber compound is a mixture of natural rubber, styrene-butadiene rubber, cis-butadiene rubber, isoprene rubber, chloroprene rubber, and nitrile rubber, and the mixture is obtained by blending multiple rubber compounds; During blending, nitrogen gas is injected into the cylinder from the bottom through the air inlet via the injection pipe. The gas forms bubbles in the adhesive solution and rises, while being broken up by the stirring shaft, causing the adhesive solution to exhibit a "boiling" state similar to a fluidized bed. This promotes thorough mixing of the adhesive solution and eliminates dead zones caused by shearing and stirring. The stirring shaft rotates at 500~1000 r / min. For gas pressure selection, the injection pressure is chosen to be 1.5-3.0 MPa, and the flow rate is 30-150 L / min. After blending, a blended adhesive solution is obtained. Temperature control is used during the blending process, controlling the temperature of the injected nitrogen gas between -20℃ and 0℃, and controlling the temperature of the adhesive solution during blending to not exceed 30℃. (3) Mixing of slurry and adhesive Rubber slurry is added to the mixing device, then the device is started and the silica slurry is added, and shearing, stirring and dispersing are performed; A multi-stage variable frequency stirring method is adopted. During stirring, after a stable flow field is formed, variable frequency reverse stirring is performed to accelerate the stirring speed and generate a large stirring force, which breaks the already stable flow field of the adhesive and further disperses the silica and fine particles in the slurry. During the blending process, the speed range is 500~1500rpm, and 25 speed and direction changes are performed. The speed difference for each speed change is 400rpm, and the speed change process is completed within 10s, resulting in a speed acceleration greater than 40r / ms.
2. The method for blending slurry and adhesive solution suitable for rubber production according to claim 1, characterized in that, In step (1), the slurry contains 10-150 parts of silica, 0-30 parts of silane coupling agent, 0-5 parts of zinc oxide, 0-4 parts of stearic acid, and 0-8 parts of antioxidant.
3. The method for blending slurry and adhesive solution suitable for rubber production according to claim 2, characterized in that, In step (1), the organic solvent is an alkane.
4. The method for blending slurry and adhesive solution suitable for rubber production according to claim 3, characterized in that, In step (1), the ratio of the formulation components to the solvent is 1:10 to 1:3, and the mixture is stirred at 20±10℃ for 1 to 10 hours to obtain a slurry.
5. A mixture of slurry and adhesive obtained by the method according to any one of claims 1-4.
6. A method for preparing rubber using the mixture according to claim 5, characterized in that, The mixture is coagulated and desolventized, then filtered, dried, and extruded into sheets to obtain the final rubber.